BACKGROUND: The aim of this study was to compare influenza immunization rates in children who were defined as high risk for complications following a letter or a phone reminder, and to survey parental opinions about influenza.METHODS: The 198 families of 930 children were targeted. After the season for immunization, a phone survey was conducted.RESULTS: A letter was sent to the families of 444 children. A telephone reminder was successful with the families of 288 children. The rates of influenza immunization were 15.3% and 13.5%, respectively. In the 86 families that were interviewed, 46.7% of the children in the families who got a reminder letter were immunized compared to 32.1% in those who got a phone reminder (P=0.184). Better knowledge, older parents, and larger families were associated with higher immunization rates. Major reasons for non-immunization were: potential side effects, lack of knowledge, and opposition to influenza vaccine.CONCLUSIONS: A reminder letter or a phone call did not lead to high rates of influenza vaccination in children, nor was there significant difference between the two reminder methods. Parental knowledge, attitude, and barriers for vaccination should be addressed when a reminder method is chosen.